1. Field of the Invention
The present invention relates to resins or waxes made by reacting isocyanates with selected nucleophiles such as alcohols and/or amines. The nucleophiles can be used singly or in combinations to achieve certain desirable properties in the resins. The present invention also relates to phase change ink compositions, both generally and in specific compositions, containing such resins and/or waxes. More particularly, the present invention employs the use of an isocyanate-derived urethane/urea resin, which is the condensation reaction product of at least one alcohol precursor, an isocyanate precursor and at least one amine precursor. The present invention also covers a phase change ink carrier composition and the ink formed from the isocyanate-derived resin, a tackifier resin, a mono-amide and a colorant. Still further, the present invention relates to the process of using such phase change ink compositions containing such resins and/or waxes in a printing device.
2. Description of the Relevant Art
In general, phase change inks (sometimes referred to as xe2x80x9chot melt inksxe2x80x9d) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the Jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the printing media, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks have also been investigated for use in other printing technologies such as gravure printing as referenced in U.S. Pat. No. 5,496,879 and German patent publications DE 4205636AL and DE 4205713AL assigned to Siegwerk Farbenfabrik Keller, Dr. Rung and Co.
Phase change inks for color printing generally comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. Preferably, a colored phase change ink will be formed by combining the above-described ink carrier composition with compatible subtractive primary colorants. The subtractive primary colored phase change inks of this invention can comprise four component dyes, namely, cyan, magenta, yellow and black. U.S. Pat. Nos. 4,889,506; 4,889,761; and 5,372,852 teach that the subtractive primary colorants employed typically may comprise dyes from the classes of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and a limited number of Basic Dyes. The colorants can also include pigments as exemplified in U.S. Pat. No. 5,221,335, assigned to Coates Electrographics LTD. U.S. Pat. No. 5,621,022 issued Apr. 15, 1997; and assigned to Tektronix, Inc., is directed to the use of a specific class of polymeric dyes in phase change ink compositions.
Phase change inks are desirable for ink jet printers since they remain in a solid phase at room temperature during shipping, long-term storage, and the like. Also, the problems associated with nozzle clogging due to ink evaporation are largely eliminated, thereby improving the reliability of ink jet printing. Furthermore, in the above-noted prior art phase change ink jet printers where the ink droplets are applied directly onto the printing medium the droplets solidify immediately upon contact with the substrate, migration of ink along the printing medium is prevented and dot quality is improved. This is also true of the processes and ink compositions described herein.
In addition to the above-referenced U.S. patents, many other patents describe materials for use in phase change ink jet inks. Some representative examples include U.S. Pat. Nos. 3,653,932; 4,390,369; 4,484,948; 4,684,956; 4,851,045; 4,889,560; 5,006,170; and 5,151,120; as well as EP Application Nos. 0187352 and 0206286. These materials can include paraffins, microcrystalline waxes, polyethylene waxes, ester waxes, fatty acids and other waxy materials, fatty amide-containing materials, sulfonamide materials, resinous materials made from different natural sources (tall oil rosins and rosin esters are an example) and many synthetic resins, oligomers, polymers and co-polymers.
Separately, PCT Patent Application WO 94/14902, which was published on Jul. 7, 1994 and is assigned to Coates Brothers PLC, teaches a hot melt ink containing a colorant and, as a vehicle for the hot melt ink, an oligourethane having a melting point of at least 65xc2x0 C. and obtained by reacting an aliphatic or aromatic diisocyanate with at least a stoichiometric amount of either: (i) a monohydric alcohol component; or (ii) a monohydric alcohol component followed by another different monohydric alcohol component; or (iii) a monohydric alcohol component, followed by a dihydric alcohol component, followed by a monohydric alcohol component.
This PCT patent application defines the monohydric alcohol component as either a monohydric aliphatic alcohol (e.g. C1 to C22 alcohols), an etherified dihydric aliphatic alcohol (e.g. propylene glycol methyl ether (PGME), dipropylene glycol methyl ether (DPGME), ethylene glycol butyl ether (EGBE), diethylene glycol butyl ether (DPGBE), tripropylene glycol butyl ether (TPGBE) and propylene glycol phenyl ether (PPL); esterified dihydric aliphatic alcohol (e.g. the esterifying acid may be an ethylenically unsaturated acid (such as acrylic acid or methacrylic acid), thereby introducing ethylenic unsaturation into the oligourethane and rendering it suitable for eventual further additional polymerization (curing) after having been applied to a substrate by hot melt printing), or dihydric polyalkylene glycol. This PCT Application further defined the dihydric alcohol component as a dihydric aliphatic alcohol or a dihydric polyalkylene glycol (e.g. ethylene glycol, polyethylene glycol (PEG 1500), polypropylene glycol (PPG 750, 1000 and 1500), trimethylene glycol, dipropylene glycol, methylpropanediol and 1,6-hexanediol).
Also, PCT Patent Application WO 94/04619, assigned to the General Electric Company, teaches the use of ionomeric materials in combination with image forming agents to form a hot melt ink jet ink. The ionomeric materials can include many different types of copolymeric or polymeric ionomers, including carboxyl-functional polyurethanes prepared from a diol or polyol and a hydroxyl acid. Many other carrier materials and colorants for the image forming agent of the invention are included in this PCT application.
U.S. Pat. No. 4,665,146 discloses the use of monoethylenically unsaturated monomers that are polymerizable precursors used to produce aqueous coating compositions by reacting a diisocyanate, a monoamine and a monoalcohol. The reaction product is reactive and is disclosed as being in a solution.
There is still a need for new materials for novel and different applications of phase change inks. There is a also a need for relatively low viscosity resins, including non-polymeric resins, and waxes designed for phase change ink jet and other forms of phase change ink printing. These needs are solved by the present invention by providing a means to tailor the properties of a resin or an isocyanate-derived material for specific applications.
It is an aspect of the present invention that urethane compounds comprising the reaction product of selected isocyanates with selected alcohols or mixtures of selected alcohols are obtained.
It is another aspect of the present invention that urea compounds comprising the reaction product of selected isocyanates with selected amines or mixtures of selected amines are obtained.
It is still another aspect of the present invention that urethane/urea compounds comprising the reaction product of selected isocyanates with mixtures of selected alcohols and amines are obtained.
It is still a further aspect of the present invention that a reaction product of a selected alcohols or mixtures of selected alcohols, an isocyanate, and a monoamine is obtained that can be used in a phase change ink composition.
It is a feature of the present invention that the reaction product is an isocyanate-derived material.
It is another feature of the present invention that the colorless isocyanate derived material or resin reaction product of the selected isocyanates with selected alcohols or mixtures of selected alcohols and/or selected amines or mixtures of selected amines obviates the need for the use of a separate plasticizer when the material or resin is employed in an ink formulation because the resulting ink is sufficiently malleable and ductile on its own.
It is an advantage of the present invention that the isocyanate-derived material or resin reaction product can be design engineered to obtain desired properties for specific printing platforms and architectures.
It is another advantage of the present invention that the isocyanate-derived materials or resins are very pure, being free of salts and other insoluble contaminants.
It is still another advantage of the present invention that the isocyanate-derived materials or resins can be used in combinations with other phase change ink carrier materials to obtain ink compositions that display improved yield stress versus temperature curves over prior art ink compositions.
It is still another advantage of the present invention that the isocyanate-derived materials or resins are nonethylenically unsaturated stable solids.
It is yet another advantage of the present invention that the isocyanate-derived materials or resins are transparent.
It is yet further advantage of the present invention that the isocyanate-derived materials or resins may be substituted for one or more components in prior fatty amide containing phase change inks, such as the tetra-amide, mono-amide, tackifier, or plasticizer components.
These and other aspects, features and advantages are obtained by the use of reaction products of selected isocyanates with selected alcohols and amines to produce isocyanate-derived material or resins. These materials are suitable for use in phase change inks that may be employed in direct or indirect printing applications.